Conventionally, an embroidery unit for sewing embroidery on a workpiece cloth clamped by an embroidery frame has been provided either separately to or integrally with an electronic sewing machine. Under such configuration, the embroidery unit is driven in accordance with embroidery data to carry the embroidery frame in a width direction (Y-direction) and a length direction (X-direction) of the sewing machine bed to form embroidery seams.
JP-A-2002-52280 (hereinafter referred to as patent document 1) discloses an embroidery frame carrier unit detachably attached to the sewing machine bed. The embroidery frame carrier unit includes a carriage removably receiving a connecting portion of the embroidery frame; a Y-direction carrier mechanism carrying the carriage in the Y-direction; and an X-direction carrier mechanism disposed below the Y-direction carrier mechanism to carry the carriage in the X-direction in cooperation with the Y-direction mechanism (refer to FIG. 8 of page 5 of patent document 1).
Provided on the main casing of the embroidery frame carrier unit is a movable case containing the Y-direction carrier mechanism and the carriage. The movable case appears as a projection atop the main casing and further extends beyond the foremost end and the rearmost end of the casing.
The embroidery frame carrier mechanism disclosed in patent document 1 requires a troublesome task of detaching the embroidery frame carrier unit from the bed in case the user desires to execute normal sewing operation such as utility sewing after embroidery sewing operation. One solution may be to allow the execution of normal sewing without having to remove the embroidery frame carrier unit from the bed. However, in such case, the movable case provided on top of the main casing in a projecting manner is likely to interfere with the normal sewing operation, leading to low work efficiency.
Also, the increasing demand to sew large embroidery patterns calls for a larger movable case projecting further forward and rearward relative to the bounds of the main casing, which in turn requires larger space to store the embroidery frame carrier unit when it is not in use. Also, larger movable case requires larger packaging supplies for packaging, creating problems such as increase in cost and effort.
One solution to such problem is allowing the movable case to be removed from the embroidery frame carrier unit on a required basis. However, such configuration additionally requires a complex mechanism for detaching the Y-direction drive mechanism containing the movable case from the X-direction carrier mechanism inside the main casing. This inevitably leads to cost increases of the embroidery frame carrier unit. Also, such detachment mechanism is highly prone to rattle at its joints, which may reduce the precision of positioning the embroidery frame and causing pattern distortions.